Why in news?
Weather agencies reported that a new western disturbance would approach northern India between 11 and 13 May, bringing clouds and possible rainfall. The previous disturbance weakened as it moved eastwards, giving a short break from rain across Punjab, Haryana and Delhi. Farmers and officials are watching the next system closely because such storms can affect crops and daily life.
Background
Western disturbances are extra‑tropical storms that form over the Mediterranean Sea and move eastward with the high‑altitude jet stream. As they travel across Iran, Afghanistan and Pakistan they gather moisture from the Mediterranean, Caspian and Black Seas. When they reach India they bring gentle rain or snow to the northern plains and Himalayas during winter and spring.
Key points
- These storms are called “western” because they arrive from India’s western side. They are not part of the summer monsoon.
- Winter rain from western disturbances is crucial for rabi crops such as wheat and mustard. It also replenishes rivers and reservoirs across the Indo‑Gangetic plain.
- The storms usually develop when a high‑pressure area over Eastern Europe pushes moist air southwards. A trough in the jet stream then draws this air toward India.
- Climate scientists have observed that the number and strength of western disturbances vary from year to year. In some years weaker disturbances lead to dry winters, while in others stronger systems cause heavy rainfall and even hailstorms.